Is it possible to add 3 number custom field value and show it in a new number custom field?

[MANISHA KAUSHIK]

Is it possible to add 3 number custom field value and show it in a new number custom field?

I have to add 3 number custom field (Named as CF1, CF2, CF3) and has to store it in a new number custom field(CF4). The custom field CF4 is a read only field.

I even wish to change the values of CF1, CF2, CF3 and the values in CF4 should be updated accordingly based on changes made on the same screen where the values of CF1, CF2, CF3 will be updated.

As of now, I am able to make the custom field CF4 as read only. And also the CF4 value is getting calculated. But, if all fields are on the Edit screen and if I am opening the edit screen and I am making the changes on CF1, CF2 & CF3, then the CF4 is not getting updated with new values, rather it is storing exact one step old values on the view screen. But, when I am again editing the issue and without making any changes I am just editing/ reviewing the screen then the new changes get updated on the view screen. 

Could anyone suggest me with a feasible solution here to update the calculated values in CF4 as soon as the values are entered/ edited/ modified in CF1/CF2/CF3.

[Nicolas Werle _Decadis AG_]

Hi @MANISHA KAUSHIK 
Jira Workflow Toolbox provides calculated number fields. With this plugin you can create a read-only custom field CF4 which calculates the total of CF1, CF2 and CF3. 
Best,
Nicolas

[MANISHA KAUSHIK]

Hello @Nicolas Werle _Decadis AG_ ,

Is there any other way to add the values of all the 3 CF to one CF by script runner or by behavior as it is for one specific project only.

Best Regards,

Manisha